The present invention relates to an endoscopic diagnosis system for performing narrowband light observation and autofluorescence observation as special light observation.
There is conventionally used an endoscope device wherein white light (normal light) emitted from a light source device is guided to the tip of an endoscope to illuminate a region under observation of a subject, and the reflected light is imaged to acquire a normal light image (white light image) in order to perform normal light observation (white light observation). In recent years, there is used an endoscope device wherein a region under observation of a subject is illuminated by narrowband light (special light) having a given wavelength range, and the reflected light and autofluorescence are imaged to acquire a special light image in order to perform special light observation in addition to normal light observation. See JP 2007-50106 A.
An endoscope device capable of special light observation can readily visualize biological information on, for example, a fine structure of a new blood vessel formed in a mucosa layer or beneath a mucosa layer in a subject's lumen and enhancement of a site of lesion, which is unobtainable from a normal observation image. When, for example, the site to be observed is a cancer-affected region, illuminating a mucosa tissue with blue narrowband light enables observation of fine blood vessels in the superficial layer of a tissue and a fine structure in greater detail and thus permits diagnosis of a site of lesion with an increased accuracy.
As illustrated in a conceptual view of FIG. 11, the electronic endoscope described in JP 2007-50106 A illuminates a site under observation with one kind of excitation light, and images the reflected light thereof with a first sensor (image sensor) having blue filters to obtain a narrowband light image while simultaneously imaging the autofluorescence with a second sensor having green and red filters to obtain an autofluorescence image in special light observation mode.
In the normal light observation mode, white light is allowed to illuminate the site under observation, with a blue filter that only passes excitation light having a wavelength range of 400 nm to 500 nm located in a position off the optical path, and the reflected light thereof is imaged by the first and the second sensor. The process generates a video signal of a normal light image composed of red, green, and blue light consisting of a blue color signal of the first sensor and a green and a red color signal of the second sensor.
In the special light observation mode, a blue filter is positioned on the optical path to allow excitation light having a wavelength range of 400 nm to 500 nm to illuminate the site under observation, and the reflected light thereof and the autofluorescence are imaged by the first and the second sensor. The process simultaneously generates a video signal of a narrowband light image composed of a blue color signal of the first sensor and a video signal of an autofluorescence image composed of a green and a red color signal of the second sensor.